In terms of amount of the deviation at near and distance fixation, XT has been distinguished into four patterns (basic, convergence insufficiency pattern, divergence excess pattern, and simulated divergence excess pattern), according to the classification proposed by Duane [1].

The 15-question pencil-and-paper Convergence Insufficiency Symptoms Survey (CISS) questionnaire was completed during each data collection session by selecting the frequency of the particular near vision symptom (Figure 2).

A recent Romanian study revealed that roughly 3 in 5(60.4%) of young adult patients complaining of blurred vision at near work suffered from convergence insufficiency. Similar studies conducted by Southern California college of optometry found that approximately 1 in 8 i.e.

According to two separate studies, there is a "high occurrence" of convergence insufficiency (CI), a vision disorder that causes the eyes to move outward, among children with attention-deficit/hyperactivity disorder (ADHD).

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